Long known for its role in helping blood clot after you get a wound, it turns out that this nutrient also helps build strong bones. Two large studies, the Framingham Heart Study and the Nurses' Health Study, have linked lower intakes of vitamin K to a higher risk of fractures. And a study in the Feb. 1, 2008, issue of the American Journal of Epidemiology suggests that it might protect the bones and offer other health benefits, in part by reining in chronic inflammation.

Some researchers think that the current recommended intake of 90 micrograms for women and 120 micrograms for men may be too low. The best dietary sources of vitamin K are green, leafy vegetables and canola, olive, and soybean oils. If you seldom eat K-rich foods, you might consider a multivitamin or calcium supplement that contains the vitamin. But talk with your doctor if you take blood thinners, which could be undermined by changes in vitamin K intake.